The invention relates to the general field of aviation.
It relates more particularly to non-destructive inspection of aviation parts, such as parts for aeroengines, e.g. such as high pressure or low pressure turbine blades, nozzles, etc. Nevertheless, no limitation is associated with the type of aviation part under consideration, nor with the material out of which the part is made. By way of example, the material may optionally be a composite material.
In known manner, the term “non-destructive inspection” is used to designate a set of methods that make it possible to characterize the state of the integrity and/or the quality of structures or of materials without degrading them. Non-destructive inspection has a preferred but non-limiting application in the field of aviation, and more generally it is applicable in any field in which the structures for which it is desired to characterize their state and/or their quality are expensive and/or in which it is critical that those structures operate reliably. Non-destructive inspection may advantageously be performed on the structure or the material under consideration both during production and also during use or maintenance.
Among existing methods of non-destructive inspection, some rely on digital images provided by digital tomography or X-ray systems. The advantage of such images is that they provide directly-usable information about the insides of structures or materials, and thus make it possible to detect internal defects that might affect those structures or those materials, e.g. such as the presence of inclusions or of cavities due to shrinkage. In the description below, the term “part” is used more generally to designate the structure or the material on which non-destructive inspection is to be performed.
Numerous variables are involved in setting up the above-mentioned digital imaging systems in order to acquire digital images of parts that are to be subjected to non-destructive inspection. Such variables include in particular the magnification, the time the part is exposed to electromagnetic rays (e.g. X-rays), pixel size, the quantum detection efficiency of the sensor forming part of the digital imaging system, etc. Nowadays, these settings are defined and validated for various measurement ranges by certification committees known (in France) as COSAC 2 and COSAC 3 (COmité Sectoriel Aérospatial de Certification [Aerospace Sector Certification Committee]). They rely to a very large extent on the experience of the professionals who manipulate digital imaging systems and on image quality indicators (IQIs) or factors being measured over a wide range of conditions on digital images in two or three dimensions that have been obtained from the digital imaging systems under consideration. Thus, at present, “manual” optimization of the settings of digital imaging systems such as tomographic or X-ray systems implies a considerable amount of work and time, and is to a large extent dependent on the ability of the person doing the optimization.